1. Field of the Invention
The present invention is directed to a defibrillation electrode of the type for implantation at an intravascular site in a patient.
2. Description of the Prior Art
Defibrillation electrodes are known for implantation at an intravascular site in a patient, these known electrodes generally including a flexible electrode cable containing at least one elongate, electrically insulated conductor with an electrode head, arranged at the distal end of the electrode cable, the electrode head having at least one defibrillation surface for delivering defibrillation pulses to the heart.
One such known defibrillation electrode intended for intravascular implantation is described in European Application 0 373 953. The electrode head of this known defibrillation electrode is a continuation of the electrode cable, and thus the diameter of the electrode head is approximately the same as that of the electrode cable. A disadvantage of this type of defibrillation electrode is that the electrode head cannot be affixed when sited in a blood vessel. Since a defibrillation electrode of this type is always a part of a defibrillation system with a plurality of defibrillation electrodes, longitudinal displacement of the electrode head can result in an undesirable distribution of the current in the heart, since the current distribution is a function of the relative location of all of the electrodes comprising the electrode system. Another disadvantage of this known electrode is that the electrode head is disposed in the bloodstream of the vessel in which it is sited without any lateral control. This can result in an obstruction of the blood flow and also increases the risk of clot formation.